Top Of The World
by KiwiRaptor
Summary: It's been years since that tragic day and Hiro finally gets his second chance. Though it isn't exactly what he imagined, he'll take it, doing everything and anything he can to ensure that his brother lives, no matter what the cost. Timetravel AU.
1. The Door

Sunlight streamed into the room belonging to the brightest mind of San Fransokyo, Hiro Hamada. The robotics prodigy and local genius lay reclined in his chair, long fingers tapping along the edge of the keyboard that rested in his lap. Slanted eyes quickly scanned whatever document was captivating his attention as a hand came up and mindlessly brushed hair out of his face. He remained still until moving onto the next document, skinny shoulders slumping as he leaned his cheek against his fist, expression immediately turning into one of boredom. Somewhere, a phone buzzed.

Sluggishly fishing the device out of his pocket, the teenager glanced at the caller ID before answering, "I swear Fred, if this is another call begging me to create a serum that induces spikes to grow along your spine, my answer is still no. "

"No, it's not-" Came his friend's muffled voice.

"It's impractical at best." Hiro swiveled in the chair, cutting his friend off while he dumped the keyboard among the chaotic mess of his desk. He flicked some hair out of his eyes again and said, "It would get in the way of everyday stuff, for one. Plus, it would look kinda weird, you know, with just random spikes. What would you even need them for?"

"I'm not calling for- Wait? Impractical? No, no, no, little man, you gotta see the overall picture. Spikes have so many uses, like-" Fred's monologue was cut short by a curse, causing Hiro to start, hand going out to brace against his desk, effectively stopping his revolution. The younger boy heard a scuffle on the other end of the call and stood up, mouth opening to say something.

"Hiro?"

"GoGo?" He breathed a sigh of relief at the familiar voice. "Phew, I thought something was wr-"

"Callaghan escaped prison."

And just like that, all the air escaped him. He nearly dropped the phone, wide eyes resembling saucers. He muttered a small 'ow,' the phrase almost involuntary, and heard the reassuring beep, beep, beep as Baymax inflated into existence.

"What? When did this, when did he… H-How?" Hiro stumbled over both his words and the items scattered around his bedroom floor as he tried to get ready. He shrugged on one of his older jackets, one that he hadn't outgrown in one of his many growth spurts a few years back, and thankfully located his backpack under a mess of clothes, shouldering it. "Where is he now?"

"We don't know yet. But we have a pretty good idea where he's going." Came her curt reply. Hiro nodded to himself as he ignored Baymax's polite 'Good morning, Hiro. I hope you had a balanced breakfast' and grabbed the robot's arm, hauling him down the steps to his Aunt's cafe.

"Krei Tech."

* * *

><p>Big Hero 6 landed outside of the building of Krei Teck within minutes of the call, the clear ringing of the alarms in the air and deafening. Alistair Krei himself was there to greet them, looking both worried and angry. Along with him was his secretary and a few guards who didn't look any more composed than their CEO. Within seconds of their landing, Hiro's feet barely touching the ground, Krei was on them, with his people close behind.<p>

"How could you let that- that maniac escape?" The man hadn't changed much over the years, looking just as professional with his tailored suits and perfect hair as he had when they first met, though there was a wrinkle or two that was new. Right then, he looked a little more shaken, his hair not as neat and his clothes a bit more crinkled, his voice dominating over the others. "You know that he has it out for me!"

Hiro resisted the need to roll his eyes, used to the man's attitude, briskly walking past him and forcing him to follow to continue on. The team followed, the sound of Baymax informing one of the guards that he had too high a cholesterol and should respond accordingly in the background.

"I didn't know our job description included babysitting criminals day-in and day-out."

The entrepreneur frowned, eyes narrowing at his remark, "No, only the lunatics."

Now it was Hiro's turn to frown. Some part of him wanted to defend the once well-renowned scientist, as it always did when confronted by people who talked badly of the man, but he held it in. Although the man had spiraled toward madness, using violent methods to reach his goals no matter the consequences, there was reasoning behind all it. Reasoning that he understood, something that others never really bothered to look more into, just labeling the actions of that of a madman.

"So what's the situation here?" He asked, wanting to stay clear of the earlier conversation. Krei was now leading them down a large, sloped hallway, a red light pulsing along with the alarm every ten feet.

"He's on level B, which is right below the basement. All the staff was evacuated- which isn't good for business, let me tell you, and I'll probably lose a fortune over today's setback." The younger man gave him a pointed stare, causing the entrepreneur to cough into his fist awkwardly. "Right...well, we don't know what he has on him and I'm not going to risk my entire company on a man who may or may not have control of thousands of tiny robots."

After a quick glance at the others, Hiro refrained himself from mentioning that there was only a handful of microbots still in existence, all of which were sitting in a small jar atop of his dresser back home.

"How did he get down there?"

Krei's assistance spoke up, "Our system was revealed to have been hacked."

Hiro managed to stifle the snort threatening to break through. Callaghan was a well-renowned scientist throughout the world, he had the intelligence to receive such recognition and respect, but Krei Tech wasn't as advance and amazing if a single man could break in with only a day's notice (even with Callaghan's level of aptitude).

"What's he doing down there anyway." GoGo asked, both Hiro and her zeroing in on the way the older man hesitated. She popped her gum, deliberately chewing loudly as she stared at the sweating man.

"Yeah, it's not like you have any top secret projects down there that can ultimately end the world as we know. Like in issue thirty-three of-" Honey Lemon efficiently shut Fred up, elbowing him just above his kidneys, somehow finding purchase through his thick costume, causing the other to yelp girlishly.

Krei fiddled with his collar, looking like he was in an interview gone wrong, not answering.

"Oh no. There's something really dangerous down there, isn't there?" Worry colored Wasabi's voice, his hands flapping up and down in anxiety, voice rising in pitch, despite his experience with these sort of situations. His question remained answerless. "No, I don't even want to know… wait, yes I do. What's down there?"

Krei opened his mouth-

"Is it some kind of huge mech robot? With, like, advanced lasers and guns. Is it the Missing Link? I bet it's the Missing Link. Or maybe it's a death ray. Those are awesome. I mean, I've never actually seen one in person, since Wasabi said it was a stupid idea, but I bet it's really awesome-"

"Now is the time to stop," Wasabi held up a hand, glaring at Fred. "before I slap your face off."

"Mr. Krei..." Honey supplied helpfully, making a gesture for him to continue.

The man loosened his tie, "It's, well, a continuation of Silent Sparrow."

There was a short duration where no one spoke. It was a quickly broken by the whispered shouts of the team.

"Are you serious?!" GoGo hissed, face contorting in anger, "Why on earth would you do that? Especially what happened because of it."

They all tried their best not to flinch when he set his shoulders back and said, "The world goes on despite the end of our own. Despite the losses, I will make sure advancements are made."

He walked on, not turning back to see their pained expressions, entourage faithfully following him. Hiro forced himself not to look at the rest of the team, unwilling to think about tragedies that never fully healed with time, and moved to follow the businessman.

Finally, they came to a door, reinforced to such a degree that Hiro almost felt intimidated. Which was absurd, because it was just a door. Krei stepped up to it, placing his hand on a scanner that protruded from a wall and waited for it to grant them access. There was a release of air and suddenly they were stepping into a room not unlike the one that housed the portals on Akuma Island so long ago.

In the center of the room was something that looked vaguely like the portal Hiro remembered swallowing Krei Tech years before. It looked more like a giant doorway than a portal, but that didn't stop Hiro from gazing at it in awe. Wires connected its metal frame to multiple console stationed behind and next to the device. Something was humming, the sound so low that he couldn't quite place where it was coming from.

There was some sort of podium where Hiro assumed a control panel possibly stood, the only fact confirming this being the figure currently hunched over it. It was Callaghan, still his prison garb.

Hiro tried not to let it show how much it hurt to see the man responsible for his brother's death, out and about, and not behind bars. He swallowed loudly, pushing those vulnerable feelings somewhere they couldn't hurt him, and stepped forward.

"Callaghan." He called out across the room.

"What? No Professor?" The older man didn't even twitch, eyes never straying from whatever task he was trying to get done. However, the man was spitting his words, shoulders hunched and face drawn in obvious anger. "No one respects their elders as they should nowadays."

"You lost that respect the night you let innocent people die for your revenge." The answer immediate, brown eyes hardening. Hiro could practically feel the worried stares of his teammates directed at his back and he drew strength from their presence.

The older man's hands momentarily froze, but they soon continued their work, seemingly faster than before.

"What are we waiting for? Let's kick this guy's butt!" Wasabi, usually so grounded, exclaimed. Plasma blades shot out of his forearms, buzzing when he moved even in the slightest. He was stopped from taking a step forward and initiating the battle to begin, Gogo's small hand holding him back with a stone grip. She nodded toward the genius clad in purple, her voice clear and final.

"We do this Hiro's way."

There was an unspoken message passed through them all at those words, one that had them relaxing from their battle stances. Callaghan was the first villain any of them had faced, but he was more Hiro's decision than theirs.

Tadashi had been their friend, but he had been Hiro's brother.

Hiro was about to say that he didn't mind just kicking the crazed man's butt all the way back to prison, but found himself stopping those words. He blinked, confused at the realization he had come to so suddenly. He did not, in fact, want to hurt Callaghan.

This man, driven by thoughts and emotions he, himself, could so easily relate to, had taken a road that could have been Hiro's under different circumstances. He could have just as easily zoned in on the anger and resentment of losing a loved one, wanting to carry out the "justice" that his murderer so rightly deserved. He almost had, in the beginning. The genius didn't like to imagine what he would've done if that anger and grief had won out, the thoughts giving him chills.

He pitied the man.

Pitied him because he had chosen anger over forgiveness, hate over love, and now, when everything was said and done, had truly nothing left to fall back on. He was a broken bot with no purpose. Looking at the fallen man, guilt washed over Hiro, his mind going back to times where he unthinkingly saw the man as mad like everyone else, not bothering to understand.

He needed to help him, be there for the man as his friends were for him, even if it was long overdue.

"Professor Callaghan," he began, thinking Tadashi would have tried to talk things out, violence never being the answer in his book. "What are you doing? What's the point of all this?"

"I want a better life. A life where I have my daughter back, where I can see her, where I can be with her." He paused to swallow, a flash of guilt settling on his face before it was replaced by one of determination. "And I can't have that in this one."

He flipped a switch from the sea of many, the low hum of the machine increasing as the seconds passed. Lights began flickering on, sparking where wires weren't properly connected, reacting to the awakening of the portal. The lights hanging overhead tilted in the direction of the machine, some of the ripped from their wiring at the sheer intensity of whatever pull it had on them. They and other machine parts not tied down flew to the growing, swirling mass of light. Emitting a dull purple and blue hue, the portal started from the metal frames center and spread outward, its clockwise motion entrancing. Its frame vibrated in such a way that Hiro had a hard time distinguishing what was metal and what wasn't, the room shaking along with it.

There was no twin portal, giving anything swallowed no option of returning.

"The machine has been activated." Baymax supplied helpfully over the loud cries of alarm from his friends. The robot extended a massive hand toward Hiro, "I suggest you step away Hiro, as it seems the machine is highly unstable." However, said boy dodged the nurse bot's grasp, stepping away from him and towards Callaghan.

Krei blanched, backing away, fear taking over his features, "It hasn't been human tested yet! Calculations for a living organism passing through haven't been completed, the resulting effects are still a mystery-"

"Now you gain the humanity to care about the test subjects, Krei? Tell me, where was that years ago?"

The entrepreneur could only sputter in response, somehow looking a bit ashamed and furious at his former colleague's words. He seemed to know from past encounters that his words wouldn't help the situation when concerning the man. His entourage was dismantling, backing away from the machine with wide eyes, his assistant pulling at his arm, trying to guide him to safety. They all seemed to know of the danger that presented itself with the machine on and running.

Something was going to go wrong, a voice in the back of Hiro's head was repeatedly yelling out, Callaghan's different. The man was changed, with nothing to lose and everything to gain. He was a cornered animal, ready to strike out, but scared all the same.

"There are other ways, Callaghan. This isn't the only option." Hiro continued to walk toward his former idol, slow and steady steps almost seeming casual despite the strange gravitational pull that was tugging at his body, ignoring Baymax and his friends' consistent warnings.

The man shook his head, muttering to himself as he gripped the podium, knuckles turning white. "No, no, no. This is the only way I can be with my Abigail."

Out of the corner of his eye he saw the rest of the group was spreading out around the two, keeping their distance because of the machine, but slowly and surely coming closer. Krei and his group had all but left the room, a few running back through the hall while Krei and a few others were pressed and clinging against the walls. The teen turned his attention away from them and back to the man backing towards the ever glowing portal, the lighting making his face look even more tired and sunken than ever before.

"We can talk about this." Hiro finally reached the controls, hands grasping them to keep himself upright, the pull even stronger now, it taking his entire strength not to have his legs slide out from under him. Eyes glanced over the controls, glazing over momentarily when the boy realized he hadn't even an inkling of an idea of what controlled what. "You don't want to go through there. You might not make it out."

The unspoken 'alive' was left hanging, swinging before them in all its uncertainty.

The once world-famous scientist shook his head with greater passion, finally taking a step back and towards the glowing doorway, making Hiro's blood run cold. "Whether or not I die, there's still a chance. Anything will be better than this life."

And with that Callaghan threw himself back, eyes closed in twisted acceptance.

Whether or not the man had done terrible acts in the past, if there was one thing Tadashi had managed to grind into his mind, it was that no one deserved to be given up on. The teen's breath caught in his throat, eyes wide, as he fully processed what had just happened.

Callaghan was giving up, throwing everything away, and Hiro couldn't- wouldn't let that happen.

Hiro only had time for one loud "No!", hand shooting out to grab hold of the man and try and pull him back, before that strange pull yanked at him with such force that he tumbled right after him into the unknown.


	2. Here I Am

Traveling through the portal was similar to his first trip years back with Baymax, both disorienting and thrilling at the same time. The endless space that surrounded him was filled with kaleidoscopic colors, dust and cloud-like shapes shifting all around. Reds, blues, and greens- every color on the spectrum was present, some even he never knew existed- they merged and swirled about, making it difficult for his mind to comprehend it all.

It was breathtaking, all of it. His trip into the transporter years earlier was filled with hazy memories, his panic-filled mind only focusing on the danger and the mission at the time, not fully able to appreciate what had been before him in all its vast beauty. It was a mass of colors, a landscape where paint had almost been haphazardly thrown upon it, but it coming out strikingly beautiful all the same.

It was a Mandelbulb come to life, something he never dreamed of seeing, something his younger self hadn't pieced together.

The pull that Hiro felt at Krei Tech was still present, but not as violent and strong; gravity was nonexistent in comparison, the feeling of weightlessness coming over him. He felt his body drift forward not of his own accord, something setting him on a specific course to some unknown destination.

Hiro tried not to think about how lost he was and how much he wished Baymax were here, or how all his friends back home would barricade him once he got home, ranting about the danger and his lack of self-preservation. Instead, he focused on the out-of-this-world sight before him, silent and stagnant, leaving his mind to settle on the problem before him. There was a reason he was where he was.

Callaghan was in here somewhere.

It was easy to pinpoint the speck of difference in the vivid space, the dull spot that popped out like a sore thumb. And then all of the awe that he felt for this portal- universe, dimension, whatever it was- dwindled instantly, replaced by horror when his eyes found his target.

There, floating in the distance, was Callaghan.

The man was as motionless as the space surrounding him.

Hiro instantly understood, unable to stop the strangled-yet-whine-like sound that came out from the back of his throat, hand coming up to touch his helmet with silent gratitude. His breath hitched and he had to take a moment to calm himself down. He did so with only minimal success, breathing under check, though his heartbeat remained irregular and threatened to blast through his chest.

He tried not to look too closely at the body or how its eyes bulged out of their sockets and looked at him with that unnerving, blank expression. Frost covered the body, giving it an almost mannequin resemblance, making it look more and more like the corpses he usually saw in horror movies.

But this was Callaghan, he told himself, not some random character that he'd guessed would be the victim from the very beginning. He was real. Someone who he'd talked to and interacted with only a few moments ago. Someone he was trying to save. Someone he had failed.

His gloved hands curled into fists. The only thing left of Callaghan was a dead body no one would ever mourn, save him, and an infamous legacy of a broken man. It was not, he felt, what he deserved, nor what he wanted for his once-idol-turned-villain.

It was then, as he watched the body drift away, that realization hit him like a ton of bricks.

He had to find a way out of this mess, and _fast_. He had to get out before he followed the professor's footsteps and this place be branded his tomb. The portal was different than the first, he concluded, the danger amplified tenfold. Hiro remembered Krei's words on how the device hadn't even been tested properly and it suddenly occurred to him that he might die.

He wanted to panic. He wanted to scream, to cry, and to be scared out of his wits. He wanted to be five again, curled against his brother's chest as he murmured sweet nothings, dauntlessly fighting away the younger's meager fears away. He wanted to feel Baymax's reassuring hug, so warm and filled with so much compassion it was hard to believe he was a machine. He wanted someone to _be there_- but no, he was alone.

Before his could lose it he took a deep breath and tried to ignore both the nervousness settling in his stomach and the sight of the lifeless body floating in front of him. His brows furrowed after a moment or two, mouth setting with determination as he came to a conclusion.

It was time to be his own hero.

The longer he stayed where he was, he was paving his way to his grave. He considered the factors in his situation, mentally starting a timer for two- no, one minute.

His breath hitched again, suddenly making him all too aware of the exponentially decreasing amount of oxygen he had. His helmet gave him an advantage that Callaghan didn't have, but not by much. It would run out sooner than later and he would surely die, that is, if the possible radiation and decompression didn't get to him first.

There was a moment- one that he couldn't afford to lose, much less waste, panicking- where he frantically searched for an exit out of the void, the way back home. Twisting, he glimpsed the way he'd entered, seeing it almost a football field away and getting smaller. The pull had been dragging him farther and farther away, limiting his options to one.

When tears threatened to escape, only to freeze against his skin, he activated his thrusters.

Luckily, there was no debris that had to be maneuvered through this time around, for which Hiro was grateful; there was no room for error. So, following the strange pull at his center, he angled himself in said direction, catching a glimpse of swirling mass of white light ahead of him. He made sure to keep his gaze forward when he soared past Callaghan (one look and he'd break).

It wasn't until a few second passed that he started to feel lightheaded, head throbbing to the beat of his troubled heart. And it wasn't until a full thirty seconds passed from his initial count when he finally felt the pressure in his chest. What had first felt like a small discomfort to be easily ignored transformed into a undeniable ache, eventually becoming so unbearable that Hiro had to gasp for air. His mouth opened wide, nostrils flaring, as his body tried to relieve its pain.

Solution: oxygen.

Error: no oxygen present in atmosphere.

Diagnosis: suffocation

Hiro would've laughed if he had the air to spare. Even in this desperate situation, Baymax always seemed to get into the mix, his presence so consistent that the teen created his own internal nursebot when he didn't have one present with him in the material world.

Hiro felt his eyelids grow heavy and he was suddenly aware of how tired he had become. They drooped as his attempts to breath became less and less fruitful.

_No_, he warned himself, trying to kick himself back into consciousness, _don't fall asleep_.

He tried to spark his brain into activity, supplying complex matrices and quadratic equations to solve, but his thoughts and focus slipped. His mind lulled until he couldn't remember what was what or why he should even care.

The last thing he saw was a flash of white, before everything went dark.

* * *

><p>Waking up was always hard for Hiro. It was hard to leave his hazy dreams and submit to the harsh sunlight that always seemed to draw pleasure in attacking his bleary eyes.<p>

Waking up from a near death experience- now, that was something else, a whole new level of difficult, not to mention disorienting. This time around, he regained consciousness faster than he ever had in his life, but with nauseating after effects.

Brown eyes fluttered open, his body jerking awake and gasping for air. His vision flickered and the world spun, which disagreed considerably with the headache he suddenly found himself sporting. He blinked slowly as to try and make sense of what he was seeing, along with clearing his head of all the jumbled thoughts that wouldn't organize properly.

Soon enough his vision wasn't spinning and he could make out definite shapes and colors, even the occasional small detail.

Like the small detail of how he was no longer floating in a suffocating dimension.

"Wha-!" Eyes widened as he tried to jerk himself into an upright position, but only succeeded in cracking his neck painfully, making him cut off his words with a groan. He just made do with laying there longer, testing whether his body was whole, wiggling his toes and fingers. When his check came out positive he slumped completely onto the floor, boneless. He wasn't dead, the words rang throughout his mind in a continuous loop, effectively calming his rigid nerves, he wasn't dead. It didn't matter that there was something underneath him so that his back was arched uncomfortably and that he had the most horrific headache and he was probably sorer than he had been in his life, he was _alive_.

As time passed and his momentary adrenaline spike dwindled, his brain calmed, effectively allowing it to make sense of the information his senses were sending him.

And at once he could certainly say that he was in a darkened room, lying on his back and staring at a familiar tiled ceiling.

_Properly assess your health_, his inner voice, which sounded uncannily like a certain nursebot he knew, whispered, _it is your primary concern_. He did so, ignoring his surroundings once again, trying to remember the catalogued information of medicine he retained from Baymax's constant lectures.

No broken bones, but extensive bruising on his back and shoulder, maybe muscle deep, especially if his aching muscles had anything to about it. Surprisingly stiff, his armor seemed to weigh him down, pressing painfully into the more tender points of his body; the pain more focused on his right shoulder and upper back, as well as hip- he had come crashing through the portal, no doubt, leading to his current predicament. Albeit a little pained, his breathing was no longer constricted, only a bit heavy and… visible?

It was then that he noticed how cold he was- _freezing_, in fact. Shivers racked his entire frame, relentless shuddering as if he'd just come straight out of the San Fransokyo Bay during the winter. He made to hug himself and regain whatever heat he had lost, only to be met with resistance. When had lifting his hands become so difficult? Curling his fingers was almost impossible, battling the resisting force and hearing faint crackling as he did so.

He twisted awkwardly, hard to do so with the lump underneath him, trying to glimpse at whatever was on him.

A paper thin layer of frost was encasing the entirety of his armor. It looked like most of it was slowly coming off, melting or chipping off as he struggled to move his limbs. The edges and joints of his armor had larger pieces of ice wedged into their small cavities, effectively obstructing any advanced mobility, and looked to be in need of personal attention- and an appointment with a miniature chainsaw.

Slowly but surely he regained most of his motor functions back, allowing him to pull himself to his knees. Once he was able to bend his joints, brushing off the ice, his suit seemed significantly lighter. The wave of dizziness that passed was not as strong as before, making him feel a little better. As did the motion of rubbing his hands against his upper arms and thighs, the friction sparking enough warmth to get his blood flowing again and a sigh to escape his lips.

Hiro attempted to take his helmet off, only to find that it was stuck. After a few tugs, coupled with some twisting and breathless curses, he finally had the damn thing off. He discarded it unceremoniously on the ground next to him, gaping like a fish as he took a large lungful of fresh air. The air was warmer around him, making his cheeks burns, but he welcomed it, the feeling of a thousand small pins prickling his skin. His gloves followed suit, letting him get feeling back into his locked and cramped fingers.

He spent a few moments cupping his hands over his mouth, his warm breath lingering like a worried mother. It wasn't long until he felt warm enough to get down to business.

His top priority, he needed to take an inventory.

First, he took a look at his helmet, inspecting the damage. Despite the large amounts of ice, the intercom appeared to be fine. He wiped at his visor, checking on the inside whether or not anything had been fractured or crushed. Luckily, it was whole and undamaged.

Next, he checked his gloves, thankful to see that nothing seemed to be broken- he had just upgraded them not too long ago and was thankful that his work hadn't been for nothing. The capacitors in his gloves were useless, depleted of all power, which was somewhat expected, especially with how much of his suit's power had gone to his thrusters. Those were also in reasonably good shape, though he wouldn't be flying anytime soon until the ice melted completely.

Feeling at his back told him that the lump he'd been laying on had been his backpack. He was eternally grateful that Honey Lemon had gotten him to start carrying an extra set of clothes in case of emergencies. He'd have some of his tools with him too, if only a few.

Overall, his situation wasn't as bad as it could've been.

He leaned back, letting himself slouch there for a moment, thinking quickly. He needed to know the basics: what, where, how…

He _should_ take things slow, putting body over curiosity. Baymax had told him countless times that rushing through things after a strenuous ordeal would patronize his health and, although he joked and waved it aside more often than not, he knew the robot was right. Yet, despite this, once again Hiro found himself disregarding logical reasoning in favor of his antsy mind and body, both keen on answers and action.

He jumped to his feet. Well, at least, he tried to. His knees gave out a bit when having to take on his entire weight, both hands having to fly out and stop his almost face plant into the hard floor.

Wiping his palms on his pants and glancing around, the teenager took in his surroundings. He turned in a full circle, absent mindedly picking up his helmet and gloves.

Despite the earlier lack of efficient lighting, his eyes adjusted, glancing this and that way. He observed the open space and the high ceiling, which made the few lab stations spread about look tiny in comparison. And if the expensive style and technology he saw was any indicator, he knew exactly where he was.

Krei Tech.

But… that wasn't right.

It was a disaster zone the last time he had laid eyes on it. Things overturned and flying everywhere, people in disarray and scrambling to get places, alarms screeching and lighting the place a red hue. However, what he was currently looking at greatly disagreed with what he knew to be true.

He walked over to one of the stations cautiously, letting his gaze sweep over its pristine surface top and settle on a mess of papers laying there. Frowning, Hiro bent forward and squinted down at the words.

_Krei Interprise, Transportation Division, Group: 42A, Subgroup: XI, Trial: 10, Error Rating: 33.1%, Time Duration..._

He flipped through the pages, glancing over the charts and graphs, his interesting fading. It was only when he found a section dedicated to monetary values that he took a moment to raise his eyebrows, letting out a small, yet drawn out whistle, before continuing on.

_Power surges absent, stabilization of electron… _Again, Hiro went through, the information not new to him; his knowledge of quantum physics was more than adequate enough to follow the notes and reports. It isn't until he finally dwelled deeper into the notes that he slowly started to get engrossed, the science and steps behind that experiments starting to pique his interest.

_...was tasked with the purpose of collecting information describing the teleportation of material objects, providing a description of teleportation as it occurs in physics, its theoretical and experimental status, and a projection of potential applications._

Brown eyes skipped down a few paragraphs.

_Negative quantum vacuum energy can be created by a single moving reflecting surface (a moving mirror). If a mirror moves with increasing acceleration, then a flux of negative energy emanates from its surface and flows out into the space ahead of the mirror. However, this effect is known to be exceedingly small, and it is not the most effective way to generate negative energy, which is required to sustain the machine's high demands for power._

Hiro leaned in a little more, biting the inside of his lip in concentration as he glanced over a convoluted equation that held variables he had never even known existed. He'd never found a problem that he couldn't figure out, but this one was something that he'd have to look into more into, reasoning only getting him so far without the sufficient context.

Someone had scribbled something, almost indistinguishable, off to the side on one of the papers and it took Hiro a minute to decipher it. _Experiment is able to be taken step further, as the concept of moving between different points in time in such a manner is not unlike moving between different points in space__, which has been proven to be feasible._

Hiro pursed his lips, processing the information. His eyes scanned the documents once more, trying to pinpoint any information that could be of use and finding one or two parts, before moving onto the screens screwed into the wall, the bright light they were emanating causing his pupils to constrict. He brought his hand up in order to swipe at the screen, but paused, something catching his eye.

There, in the upper right corner, was a date. Today's date.

It was wrong.

All of it. The day, month, even the year. It was off, he knew. By seventeen days, two months, and four years. Exactly.

There was no need to check if the math was correct. He would forever know this one date and how much time had passed since that fateful day ever came to be. It had been painfully engraved into his mind, to never be forgotten and always sanctified.

The day he became an only child.

The day Tadashi died.

His breathing became labored, his armor seemingly squeezing the breath out of him. He couldn't move, frozen in place by burning memories.

Then, suddenly, he was sprinting to another lab station. He came crashing into the opposite wall, hands clutching at the edges of another screen and pushing him off when it displayed the same error, all the while stumbling over boxes and into stools. He jumped over a desk, papers going flying, and shoved his face up close to yet another screen, eyes going cross eyed in their effort to read the mistake.

He blinked, long and slow, taking in the date that was the same as all the others.

His mind went back to the papers and reports, to Alistair Krei's unease before encountering Callaghan, and Callaghan's own words before the portal swallowed him whole.

_I want a better life..._

"I-" His voice came out scratchy and he had to clear his throat loudly, twice. "I'm in the past?"

He put distance between him and the screen, eyebrows furrowing. He mumbled a few incoherent words, hands held out from his body as if to balance himself. He heard the crumpling of paper as he stepped back.

"How did I...?" His arms stretched high above his head as if reaching for something, like an answer to an impossibly transcendent question. After a while they came down to rest on his head while his eyes flickered across the room, both seeing and not. "The portal!"

Legs like jelly carried him back to the machine… or where it was supposed to be. There was nothing of the portal, only empty space.

"W-wha…?" Shoulders slumped while he reached out, hands grasping at nothing. An expression of utter confusion edged its way onto his face, coloring every line and smooth curve. "I don't under- What?"

Did he really believe that that was what was happening? That he'd traveled through space and time? How could he not with the evidence around him? He'd seen the data, as well as the date on the computers. Technology could be tampered with (changing a date on a computer wasn't that difficult), that was true, but that didn't explain that lack of something he knew to exist.

The answer came to him like a wrecking ball and with it, his inner nerd breaking loose.

"Oh! It's so obvious! I can't believe I didn't see it immediately!" The young genius yelled, hands making a mess of his hair while he stomped his feet, excess energy needing to be exerted. He hopped from one foot to another, excited over solving a particular puzzle. "It hasn't been made yet! Ha! It can manipulate time, but it can't break it!"

His excitement didn't last long. Soon enough it dimmed into something more humbling. He stopped moving, shoulders slumping in astonishment. His eyes widened to the size of saucers and he could feel his jaw going slack. "I traveled back in time."

He slapped himself in the face.

"Ow!" He exclaimed, traitorous hand coming up to gently rub at his cheek. He shook his head, eyes opening to the same scene he left.

"I traveled back in time." He repeated, somewhere between wonderment and confusion. "_I_ traveled back in time… I traveled back in _time_."

He let out a bark of hysterical laughter, turning his head as if to tell someone the incredulous news. Finding no one there, not even Baymax, he was instantly reminded of the situation, his mood deflating. He had traveled back, but he'd done it alone.

Alone. He was still alone. Alone in the past, on the day that had brought his world crashing down. Alone; without his friends, without Aunt Cass, without Baymax, without… Tadashi.

He had to fix things, he decided in that split moment, he had to make it better. He just had to.

And there was only one way that could be done. Of course, there were rules that he had to follow, that the entire universe followed; he, like the portal, could manipulate, but not break the time continuum. But, as long as he didn't destroy the timeline, he could change it for the better.

He could save Tadashi. That itself sounded impossible, but he'd become a part-time superhero despite the skepticism he got from that- his life was crazy to begin with, so adding one more impossible thing to the list wouldn't kill him. And if his past experiences had any inclination, he wouldn't stop until he achieved his goal.

He had to- no, _would_ save Tadashi.

It was with that resolve in mind that Hiro stepped forward, toward the door he had spied earlier, shoulders set back with determination.

That is, until somewhere, an alarm went off.

* * *

><p>AN: Took excerpts from _'Teleportation Physics Study,' Eric W. Davis, 2004 _for the lab reports.

Thanks to everyone who followed, favorited, and reviewed!


	3. 00:00

Hiro stumbled, almost falling flat on his back.

Red tinted the entire room, giving it an evil look that made his nerves scream.

He looked around him, trying to pinpoint the cause of alarm, body tensing. Finding none but himself, Hiro did the only thing that made logical sense. He ran.

The door proved to be no problem. With his running start, shouldering it open was easy, especially when he realized it wasn't locked. He stumbled, falling onto the carpeted hallway floor in a graceless heap (it did nothing for his already aching bones).Picking himself up, clumsily slipping on his gloves for when they would prove necessary, the teenager set off running with the alarm calling in his wake.

There was no time to properly calculate where he was, so he had to trust his instinct to lead him down the right path, wherever that took him. The hallway he was taking didn't look familiar, no doubt leading him further in the building rather than out. Alarmed men and women jumped out of his way, spilling whatever they had in surprise as he rushed by- he gave the occasional shove whenever encountering anyone going for any of the number of monitors decorating the walls, aiming to contact security.

Despite the alarm screaming through every speaker possible, Hiro could hear his blood rushing in his ears. His stomach rolled and his chest felt like it was being held in a tight grasp.

_To lower anxiety and lower heart rate, mediation is recommended. Breathing slowly and repetitively while concentrating on a mental image will also give a similar and effect result._

He almost made a retort aloud to his inner nursebot on how he couldn-

Voices and heavy footsteps sounded out as he rounded a corner, far heavier and more serious than those of frightened employees, stopping him short and jerking him back to reality. Turning tail, he went back the way he came, unable to hear the shouts and yells past the blaring ring going through his ears. Once catching a glimpse of a camera huddled in a ceiling corner, ominous in the red light, Hiro uttered a small curse, shoving his helmet back on.

Stairs. He had to get to the stairs. He had to get away from the prying eyes following him and the staircases were clear of surveillance, he knew.

Glancing behind him, he saw that there wasn't anyone on his tail, but he could still hear the sounds of people following and getting closer by the minute. He couldn't run all day, especially after just coming out of the portal- not unless he wanted to drop from exhaustion. If ever there was a time to find somewhere to barricade himself and catch his breath, the time was now, but he had a suspicion that he wouldn't get such a luxury so easily.

He bolted up a flight of stairs once he saw a sign directing him to the right door, practically flying, the sound of his steps echoing against the walls. With his suit's power nonexistent, he couldn't wirelessly hack into the buildings system and download its plan; for once, his usual routine wasn't plausible. None of his tech would be helping him anytime soon unless he found a way to boot it back up.

Another sign informed him that he had reached ground level and he all but leaped the last couple of steps. He hesitated in front of the door, peeking out through the slim glass frame. There were no big men waiting to pounce on him from the looks of it, the hallway devoid of people, filled with doors and glass walls and the general pristineness that Krei Tech bragged out.

Classic paranoia started to settle, the picture seemingly too perfect.

He quickly inched his way out into the open, feeling as on edge as a deer in headlights, his steps small and precise. Passing one or two vacant conference rooms and coming to an area filled with glass cubicles (a place where entropy would never reign supreme, elegant and organized to the speck), everything seemed cleared out.

"He's here somewhere. Find him before he makes off with any tech." Hiro ducked behind some desks when he heard footsteps from down the hallway he had just emerged from, watching with wide eyes and bated breath as a small squad of four security guards quickly shuffled by. One of them broke off, informing in a far softer tone than Hiro expected to the others that he was going to check the surveillance, and entered two doors to his left.

With a _hiss _and a _click_ the door closed on the bulky man, giving a short glimpse of the machinery inside before cutting it off once more. It called to him, an answer to his troubles.

Hiro rushed after the guard as soon as the rest herded themselves in some other direction, hand reaching for the door handle, only to stop as the teenager spotted the card slot fixed into it.

He whispered a curse (he'd been doing that a lot more, GoGo being far more influential than he realized) before spinning on his heel, mind whizzing about for ideas.

The answer came to him like bulldozer.

Turning a corner, he grunted when he collided with a fast moving body, sending him and the other sprawling back. Sounds of exclamation rang out; the one coming from the person he'd ran into full of indignation, while his own sounded suspiciously like a wheeze. Only taking a moment to gather himself, shaking the dizziness that seemed insistent on coming back, Hiro looked to the man picking himself from the ground in front of him.

"Krei?"

There was no doubt about it. The man in front of him was the one and only CEO of Krei Tech, down to neatly pressed suit and tie, albeit a big younger than what Hiro remembered. Seeing him only solidified the notion of where- _when_ he was; looking behind him, Hiro could see his secretary hurriedly attempting to help the disgruntled man up.

"What the-? You're not an employee! Who are you? What are you doing here?" The man demanded from the floor, questions rushing out as glared at the armor-clad teen. Paper and other assortments littered the floor around them, momentarily forgotten by the older individual. Hiro, on the other hand, spotted a simple rectangular object barely a few inches from him- an escape plan bloomed in his mind, still mediocre at best, but better than nothing. "And what on earth are you wearing?"

"Sir," the secretary said, pulling the CEO farther away from Hiro, apprehensive, "he's the one who set off the alarm- we were notified t-"

Lunging forward, having to partially crawl over the older man's legs, Hiro snatched the card, knocking the two people onto the ground once more. The woman yelped as Krei fell back, her smaller figure unable to fully support his own; they were sprawled on the floor once more.

"_Hey_!" Krei yelled, his voice following Hiro as he increased the distance between them. "Get the guards here! I want that weirdo caught!"

Gloved hands fumbled as they tried to slide the blasted card, finally succeeding after three failed attempts. He barged into the room, quickly scanning it, body already shifting into a fighting stance.

His mind processed the man sitting in a lone chair, just beginning to stand in response to Hiro's sudden entrance, and screamed for action. Without warning he swiped at the man, clipping the side of his jaw. Thankfully the element of surprise and reinforced metal gloves was a great enough advantage that the punch rendered the man unconscious. Crashing, the man took the chair with him, his temple missing the machine by centimeters.

A grunt of effort escaped his mouth when he pulled at the dead weight of the man, dragging him out of the chair and out of the way.

He stumbled over to the ajar door, slamming it shut with a resounding thud, sighing as he heard the small click of the lock that accompanied it. He closed his eyes and rested his head against the door, trying to catch his breath, despite the fact that the time he had here was fleeting.

He had work to do.

Blinking through the luminescent lighting, he identified a multitude of recognizable machines, similar to the ones found at SFIT (he was confident that they'd be easy to bend to his will). He righted the chair and plopped down into it, dumping his backpack into his lap and fishing out his memory stick. In mere moments he was in and ravaging through the building's networking.

Fingers flying, he ran through the sea of information presented to him. The building's layout was brought forward first, easy enough to find and easier to download. _The cameras_, a small voice whispered, _don't let anyone connect the dots_- for extra measure, all footage of the ground and basement level were dragged into the file he was accumulating, everything else that could've been condemning was promptly erased. It was easy enough to find things, particularly when he knew what to look for. Any file about or related to Project Sparrow, encrypted or not, was brought before him like a servant waiting on its master. Bypassing firewalls and numerous software, he connected as many networks as he could, feeling smug when it became too easy.

Tadashi had always said he could've been a leading activist if he'd been half as passionate in computer programming and software as he was in robotics.

His momentum and confidence were broken when someone banged loudly on the door, followed by angry shouting. He panicked and his work suffered because of it, mistakes popping up more often and needing to be fixed. His alarm increased tenfold when one of the hinges for the door broke loose with a twitch-inducing _snap_. He'd jerked, the computer displaying an error in his coding, setting him back further.

Then- _finally_- he finished. The system was compromised and Hiro was finally ready to make his move.

He bent down and lugged the main console for the system out from its place underneath the bulky desk, forcing himself to ignore the banging from behind that was becoming unbearable. Breaking off its outer casing and exposing its inner circuits, Hiro located the drive he needed. Flipping open a small niche in the armor of his right hand he pulled out a wire, yanking at it until its tension was at full capacity, and connected it to the mainframe.

Then, without a word, he reached over and tapped the ENTER key.

Sparks erupted from the console (_nerves and muscle may be affected by electroporation through a result of a direct lightning strike, so take precaution)_. Hiro didn't flinch, remaining silent, instead listening to the surprised yells of the people outside as the lights flickered out momentarily. He'd done this before- he knew what to do, what to expect.

No sooner had the lights returned that the sparks grew into something bigger. Thin trails of electricity crawled its way up the wire and into his suit, converting into potential chemical energy to be stored in the suit's accumulator. Skinny tendrils of the energy flickered this way and that when the amount of it became too much for the wire to properly transport, snapping at the air like a vicious dog. He could feel the heat escaping from the wire through the thickness of his suit. One of the light bulbs above him exploded, glass raining down and bouncing off his helmet; other machines flickered and some fuses blew, pouts of smoke rising up (_smoke inhalation symptoms include: coughing, shortness of breath, irritation of nose and eyes, mental confusion…)_.

His left hand came up to support his right, fingers curling involuntarily when he started feeling the strain. Still, he held out, knowing it would end soon enough. And true to his prediction, the flow of energy abruptly stopped.

The lights brightened like miniature suns before dimming into something not unlike the Singularity of a black hole. He could hear muffled voices of panicked employees as the building turned toward total darkness; the volume of it only increased when they realized that the backup generator wasn't coming into play as it should, already disabled by Hiro.

His helmet promptly lighted up, the display giving him the plans in the upper corner, numerous statistics popping up as they should, evaluating his suit's status. He was pleased to see his suit charged to full capacity and operational.

Quickly, he located the nearest exit of the building and the most efficient route to take, his screen supplying a helpful 3D model of it. He jumped from foot to foot, adrenaline pumping when he saw that he had to bypass all of the men outside.

_Not a problem_, he thought, rolling his shoulders and cracking his neck, supplying the sound when it wouldn't produce itself on its own. He smirked, confidence returning with his suit's power.

Pulling the door open with a jerk, one side of it scraping the floor because of its now lopsided nature, he lunged into the mass of people stationed there. He tapped a few of them on the shoulder, emitting the lowest possible setting he could of electrical current. Most jerked back in surprise, needing a punch or kick here and there to ensure they stay out of the equation, but a few fell, bodies going into shock because of the sudden... shock. He smiled wide when he hooked his foot around someone's knee and swept their footing right out from underneath them (Gogo would've been proud he had copied her so effectively). A few of their punches connected, but his armor did its job fine enough, preventing any lasting damage to occur. He ducked under a grab at him, his suit's sensors chiming in a warning seconds before, swiveling on his heel and grabbing the hand and throwing the man it belonged too over his shoulder with the momentum of his turn.

When enough of them were down not to hinder his escape he bolted.

He ran down the hallway, skipping through offices and confused people, only coming to a halt when he saw the blessed EXIT sign that was highlighted on his screen. He pushed against it, thanking the heavens and stars above that he had remembered to unlock all the doors before he had finished with his work. It didn't even matter that the light half-blinded him, striking at his sensitive eyes before his visor could adjust itself.

He had made it out.

In seconds his thrusters were online and, with a crouch and a leap, he was shooting up to the skyline, the blaring alarms screaming after him fading with the distance.

He spun in a circle, his wings cutting through the air with precision and ease, a bubble of laughter rising up and out of him. He angled himself towards home- towards _Tadashi_, intent on making the day end in miracles rather than disaster.

* * *

><p>It was only when he had landed, in an alleyway behind some obscure shop, that he noticed his bleeding nose.<p>

He had immediately taken off his helmet, trying hard to resist the urge to wipe at the blood, not wanting it to smudge on his gloves. Instead, pulling off a single glove, he pinched just below the bridge of his nose and tilted his head back, brown eyes staring at the clear blue sky.

_Epistaxis, or a nosebleed, is a rupture of blood vessels within the nasal cavity, _his mind supplied as he waited for it to stop, _and can be treated by applying direct pressure in a way that promotes clotting of the blood._

He grimaced as he felt some of it slide down his throat, body automatically swallowing so as to not choke. (He cursed the guard who had gotten a good enough hit at him, hoping that he had at least returned the favor.) It proved necessary to breathe through his mouth, his inhales and exhales loud in his ears. The blood that had dripped down his upper lip, which had tasted a lot like copper, began to dry into a crusty layer that pinched at his skin.

When it finally stopped Hiro dropped his hands, letting the stiffness in being held up for such a long time subside. He let himself think for a moment to decide on his next actions.

The showcase.

He needed to be there. Needed to take care of things before they went beyond his control. But how?

_Take out Callaghan._ The dark thought slithered its way into his mind, leaving a trail of even darker thoughts in its wake. _No_, he dismissed it, shaking his head in an effort to drive those thoughts away, _Stop Callaghan from making his mistake_.

_Prevent the fire._ A not-so-simple solution, as it concerned his prior thoughts. Callaghan had been the spark that started that life smoldering fire. But hadn't it been released by the authorities on a later date that the man had used a remote controlled explosive, to ensure his own safety?

If Hiro eliminated that variable…

Then Tadashi and everyone would be safe.

And afterward he would deal with Callaghan- no, not deal with, but save. He would save him. Save him from himself. He would make him see that revenge wasn't the answer, and he would succeed this time. He would succeed because he had an ace up his sleeve. His knowledge of the future.

And Abigail.

Once knowing about his daughter's vitality he would surely cease his revenge. It would bring his pain-induced madness to a screeching halt.

Bending down to pick up his helmet, he peered inside. The time programmed in it offered an unhelpful showing of 00:00. He should've guess as much, that traveling through time and space would wreck his internal clock.

He eyed the positioning of the sun in the sky, hiding behind the skyscrapers, calculating that it had to be, at least, five in the evening. The showcase, if he remember correctly, had started promptly at eight o'clock that night, the participants urged to arrive at least an hour before, but the public only gaining entrance half an hour later. That left him with a little less than two hours. A small window of opportunity in which he could act in.

He needed to scout out the hall- find where Callaghan hid the bomb. Getting in the hall should be simple; sneaking through a window, maybe on the second floor, would be best.

He nodded to himself before cupping his chin with his hand, fingers tapping against his skin.

What about his armor? He couldn't take it with him... could he?

The teenager reached behind him for his backpack, shifting it in reach. Unzipping it, he shuffled through his emergency supplies, silently thanking Wasabi for his insistence of preparation. He didn't have to dig very far before he felt the touch of fabric, recognizing the spare clothes Honey Lemon had herself insisted to be added to the list.

Lips pursed, Hiro estimated that he could at least fit his gloves and shoulder pads in the bag; maybe his shin guards too, if he pushed it. He would have to leave the rest of it somewhere- somewhere in close reach, just in case. Some ambiguous corner in the Exposition Hall, he decided, was his best bet. With the showcase going on in its ground level no one would be roaming around its higher levels, leaving it reasonably empty.

With that in mind Hiro slung his backpack over his shoulder once more, simultaneously gearing up. It was only moments before he was back in the sky, course set toward the showcase.

* * *

><p>Seeing the showcase for a second time gave him a weird sense of deja vu. The first time around he had been a nervous wreck, entirely too focused on his upcoming presentation to even think about admiring the other projects. Just like his first glimpse of the Nerd Lab he hadn't bothered to take in all that he could, more concerned about a stupid bot fight.<p>

Putting his microbots aside, the tech that was being presented bordered on amazing and downright unbelievable. Some piqued his interest, their applications bringing new options into his mind; just like how it had been with his friends and their own projects, he was being introduced to ideas he had hardly given the time of day, only to leave him awestruck at their potential (some of them being things he had believed to be fiction, only to be experienced through the screen of a television or the pages of a book). He lagged at a station with a transcranial pulsed ultrasound helmet, listening to the creator divulge on her theories and explanations, nodding along to a few and contemplating on others.

He started when one of the presenters tried to engage him in a conversation about black matter, leaning forward eagerly and peering at his face. He all but tripped his way out of there, muttering a rushed '_sorrygottago._' He pulled his hat further down, the itchy fabric rubbing against his forehead, and tightened his jacket around him when someone stepped into his path and offered a flyer. He shook his head silently, shuffling past them and losing himself in the crowd.

His legs carried him to the outskirts of the convention, where he hugged the wall and tried to melt into the shadows.

He had a job to do, he reminded himself, a mission that could not afford a possible miscalculation that a distraction provided. Even if the distractions were a few of the most interesting things he had ever encountered.

Hiro's attention shifted, eyes scanning the room. His main concern right now was Callaghan. Not once had he seen the man during exhibition, which put him all the more on edge. However, when he finally spotted the man talking to a throng of students surrounding him at the opposite end of the room, something he said eliciting a collective laugh and clapping, his nerves did not calm.

With his eyes zeroed in on the man, it was not hard to see his glances thrown toward the space just behind and below the stage, curtains expertly shielding it from curious eyes. He watched as the older man excused himself from group, all smiles and polite gestures as he made a beeline toward backstage.

Pushing himself off the wall, fists taking cover in his jacket pockets, Hiro made to follow.

He had only taken two steps before he saw a familiar blonde head bobbing above the crowd. Without prior thought he quickly sidestepped past a couple holding hands and ducked behind what looked to be a giant snow globe, ignoring the looks sent his way from the students running that station. The young man peeked his head out from his hiding place, brown eyes zeroing in on the group that was strolling past him.

It was his friends.

They were each pushing a trashcan filled to the brim with his microbots, friendly banter flowing between them with ease that came with constant interaction.

Hiro let through a small smile, head inching out more to better see them as they passed. A sense of euphoria draped over him, seeing them younger. It seemed like such a long time ago that they were relaxing about the cafe, chatting about this and that.

In the back of his mind it occurred to him that a certain person was missing, baseball cap and all.

_Stop and focus_, he ordered himself. Stepping out from his hiding place, he angled himself toward the stage.

"Oh, excuse me." A voice said as the body belonging to it accidentally shoved him, making him stumble. With it, a hand came out of nowhere, grip strong and offering a stable hold on him, "You okay there, bud?"

Freezing, Hiro's entire body seized up at the familiar sound. He imagined a boa constrictor squeezing his chest, growing tighter and tighter. Suddenly, everything was on overload. Sounds slammed into him, obnoxious and deafening, while the light attacked his eyes, a headache blossoming at his temple. Yet, none of it compared to the flood of emotion swirling in him, pulsing along with his erratic heartbeat.

He dared not believe himself when he glanced up and saw the face of the one person in the world he cherished more than anything. There, with a familiar baseball cap resting on his head and concerned expression adorning his face, was Tadashi.

_Alive and breathing and right in front of him._

Hiro wanted to speak, to latch onto his brother and never let go. Wanted to just let everything go and cry like he was four again, squished in the safety of his brother's arms. He wanted to do so much, but didn't- couldn't. Couldn't because he was frozen. Frozen in a time where his brother was dead, gone in flames and ashes, and he was left alone, pitiful and brimming with anguish as he held onto a discarded hat. Gone he was from the showcase; he was burning- screaming and weeping as the building collapsed around everything he was and cared for.

Flames licked at him in the back of his mind, yet he remained chilled to the bone. It ate at his strength, leaving him boneless. His body went numb, but he somehow managed a jerky nod.

And as he looked on at his dead brother, cataloging every feature with what little was left of his mind, his stomach lurched and rolled. He swayed while watching Tadashi continue on after a nod and smile, feeling the blood draining from his head. Then realization hit him with a ton of bricks.

There was no way he could have an episode in the middle of the exhibition. If he fainted or drew any attention, everything would turn to hell. He needed to get somewhere away.

Forcing air down his throat, he ordered his legs to take him to the nearest corridor. By the third attempt he got them to stumble forward, going in a wide circle around the carefree group of friends joking around. Thankfully, his episode wasn't so open that anyone noticed, too focused on the machinery and the upcoming presentations. Reaching a flight of steps, he slumped down, his head pressed between his knees.

He needed to relax and get through this. Now was not the time for him to lose it.

Breathe, in and out, and repeat. Repeat until his heart wasn't going to burst from his chest.

He'd gone through this before, he could go through it once more.

"Excuse me... young man? Are you feeling alright?"

It was only thanks to his predicament that Hiro didn't jerk his head up, surprised at the unexpected arrival of the man. Everything would've been lost, his cover being one of them. The tone of concern was clear, so sincere it hurt. Footstep told him that the man was getting closer.

He couldn't have that.

"It'll pass." He wheezed, squeezing his eyes, mumbling something, his fingers digging into his knees, "I'm fine."

"Are you sure? I would gladly call the nurse that's on standby. By the looks of it, you're having a sev-"

"I'm fine." His voice hardened, adamant that the man leave right then and there. Hiro couldn't help himself, he became vindictive and terse, and "I'll be _fine_."

Without looking up, he felt the eyes continue to stare, silence only broken by his hitched breathing. His neck prickled, screaming for a scratch. Then, with a few hesitant steps forward and a sigh, Callaghan returned to the main hall.

A hand came up to push at his chest, trying to knead out the pain. His heart throbbed, screaming for salvation, but only receiving more injury.

Baymax, he needed Baymax.

"Ow." Came the small whimper, only, it wasn't followed by the usual sound of vinyl being inflated. His own personal healthcare companion wasn't there, but, rather, another copy of it was somewhere backstage, dormant and unaware of his pain, waiting to be presented.

_Panic attacks, also known as anxiety attacks, are periods of intense fear or apprehension of sudden onset triggered by physical and/or emotional stimuli, accompanied by at least four or more bodily or cognitive symptoms: heart palpitations, dizziness, shortness of breath, or feelings of unreality. _His inner Baymax quoted, mind trying to fill the void the robot's absence made. _Hyperventilation, a common symptom, can be successfully suppressed with certain breathing techniques._

Hiro nodded with fervor, letting the imaginary voice of Baymax calm him.

_A 5-2-5 breath count has been proved most efficient. Using the stomach, inhale for five counts, while exhaling for two._

Listening to and following those simple instructions Hiro felt himself start to relax. His heart stopped beating like a jackhammer, ache in his chest dwindling into a dull throb.

It took a few minutes longer until he could lift up his head, even more so to stop his shaking. When he finally had the strength to clamber to his feet, body moaning and groaning in response, he regained awareness of his surroundings once more. He noticed people starting to converge toward the center stage, the show finally beginning.

He'd wasted his valuable time, no chance to get to the bomb before the presentations. His options were limited because of his stupid episode.

_Stupid, useless, worthless..._

He shuffled over, feeling vulnerable, keeping away from where Tada- his family and friends were...

Pulling his hat lower, Hiro eyed the people around him. None were paying him any heed; all eyes were slowly being drawn to the skinny kid that edged onto the stage, voice cracking as the boy tried to present his invention. Even Callaghan was there, front and center.

There was something strange about seeing his younger self in the flesh. Sure, he had seen the papers and Krei Tech and even Krei himself, but that was nothing in comparison. Tadashi had been dead and gone for years, leaving a hole in his chest, but seeing himself... he was _there_, same unruly hair and gapped tooth smile, completely unaware of the world. Innocent to all its grief and misfortune. If he didn't know any better, Hiro might have assumed someone (probably his idiotic self) had cloned him.

The photos he had flipped through with Aunt Cass on multiple occasions had never showed how truly scrawny he had been, especially when compared to his much older peers. It was all the more noticeable as Hiro stood there, watching his younger self rambling and stumbling through the presentation.

Had he really been that awkward?

Hiro caught a few people smiling, even a couple of small laughs here and there, but mainly the audience held bored and indifferent expressions. Frowning, he looked back to the stage, only to cringe as the sound emitting from the microphone made his ears ring.

A few people backed away, rubbing their ears.

Yes. Yes, he had been that awkward.

He almost felt sorry for the kid. The feeling in his stomach, so clear and unwanted, made Hiro want to leave. Secondhand embarrassment, his mind identified, slowly draining away the lingering effect of the anxiety, leaving only empathy in its wake. Empathy and a slight tinge of pity. It was hard, especially at that young age, to overcome such jitters. He'd never been, still isn't, good with crowds- or people for that matter. Give him a circuit board over human interaction any day.

_Breathe_, he mouthed to himself, only able to watch on. He saw his younger self falter, eyes seeking support; Hiro could see the exact moment when the fourteen year old found his brother, securing the resolve to continue one with a single encouraging look.

When the presentation got through its rocky start, the boy on the stage becoming for confident, Hiro smiled. He'd never been a social butterfly, but once his head and heart weren't going into overdrive Hiro knew things would get better.

Unlike the other people in the hall, who let out numerous exclamations at the black masses rushing past their feet, Hiro wasn't fazed. His younger self went on, gaining more of the crowd, his microbots finally being realized for the amazing tech they were, and soon Hiro was being squished by all the people coming forward. He struggled to remain upright and away from the stage, pushing uselessly against the overwhelming force of an intrigued audience.

At least his struggling made sure there was decent space between him and his family, him having no desire in running into them again.

Though, even amidst his annoyance, he couldn't deny that here was something invigorating about seeing the good his microbots could do, watching as his younger self listed off all the possibilities and wonders his work could do. Even with everything that had happened, he felt proud.

The applause following the presentation was deafening from his position, stunning him. Hiro looked around, taking in all the amazed expressions, watching a few talk to one another excitedly, wishing he could've saw more of this. It would have, he knew without a doubt, helped him feel better when the microbots were stolen and degraded to nothing but an evil means of inflicting harm upon others.

His breathlessness was gone the moment he saw Krei and Callaghan approach his younger self; Hiro immediately came closer, doing his best to stay hidden while still in range of hearing. When observing the older men's interaction this time around, aware of the history between the two, the tension crackling between them was clear enough. He wondered how he'd never seen it before or made an inference as to why. It would've saved so much time, and so many lives.

Then Krei left and a letter was handed to his younger self, followed by a few words by Callaghan. He made toward the group, struggling as he was going against the flow of the crowd.

A majority of the people were mingling about the stage, hoping for a glimpse at other projects. Hiro craned his neck, trying to spot Callaghan, but failing miserably; the man was probably already with the bomb, barely minutes before it went off. Fuming, he restrained himself from stomping his foot in frustration, mind already whizzing about and deciding on a course of action. Moving against the current, barely able to slip through the spaces people provided, he broke free and headed toward the door leading to the upper levels of the hall, where his suit lay waiting.

It was going to happen soon, the explosion.

And he needed to be ready.

* * *

><p>The moment he entered the main hall for a second time that night, it was to a completely different setting. Gone was the eager crowds strolling through aisles of undiscovered potential, in their place panicked masses running about like ants trying to evade a shoe. Flames licked at everything, threatening to devour anything daring to pause long enough in its path. Smoke hovered around, growing ever denser, pressing down on Hiro with animosity.<p>

The heat was almost unbearable. Hot air rushed at him, enough to push anyone back and deter further advancement. But Hiro pushed forward, suit providing protection most did not have. It was sweltering, the feeling of being cooked alive, but he strengthened his resolve.

Not spotting Tadashi within the midst of the frantic people, Hiro began to usher people out. He picked up those who tripped, handed the injured ones to others to help out, and did all he could to get everyone to safety. No one had the time to question why and how an armored individual had seemingly popped into existence, only caring that the said individual was helping.

Hiro tried not to stare too long at the burning figures lying motionless on the ground, most too far gone to be saved.

One of the showcases burst, emitting sparks that rained down on screaming people. Hiro pulled someone out of harm's way of a falling platform, urging them and a few stragglers toward the exit. His helmet magnified his orders of haste so that it could be heard over the roaring of the fire. He all but threw a familiar looking woman out the door and down the stairs, ignoring her screams and concerns of his own safety.

Soon he was the only one left within the hall.

Him and the professor.

Wasting no time, Hiro ran toward the corner of the hall holding his microbots. His helmet warned him of a falling invention, its metal frame hissing as it landed inches before him with a crash. He maneuvered around it, crying out when he wasn't fast enough to dodge a falling rod, it hitting his shoulder with a sharp _twang_. It wasn't horribly bad, most likely leaving a nasty bruise- he'd live.

Finally, he lumbered into the section of the room where he knew Callaghan to be, spotting the figure's back.

Hiro called out, desperate and unsure what to do, almost as if he was fourteen again.

Callaghan turned.

Surprise didn't cover it when the man spotted him with his suit; Hiro liked to admit that he looked a little more than just awesome, thankfully gaining some height with age. He certainly stood out in the chaotic hall.

Past the surprise, Hiro could make out the beginning of the cold demeanor that the man had displayed on Akuma Island. He could see the Yokai beginning to rise up, out for revenge and uncaring who stood in his way.

"Callaghan!"

Hardened eyes trailed over his form, upper lip curling. "Who-"

"Someone who knows this isn't what you want!" He yelled, arm cutting through the air in emphasis. Another wave of deja vu washes over him as he steps forward almost cautiously in the direction of his unstable teacher. "I know that you started this fire, that you started it to steal that tech, and that it's for your daughter- I know everything."

The man looked confused, quickly shifting to outrage.

"I don't know who you think you are, but you know _nothing_." The man spit out, voice almost lost to the flames surrounding them, the lines of his face deepening and making it look that much harsher. From behind his back, he pulled out Hiro's transmitter. "Nothing!"

"Don-" Hiro started, hand reaching out uselessly. He momentarily contemplated the idea of blasting him with an electric charge, only to dismiss it as a careless and ineffective idea. He watched helplessly as Callaghan placed the band atop his head. The microbots near the two started to shake, fueled by the man's anger.

"_Professor Callaghan!_"

The shout jolted them out of their staring contest, surprise flitting on both their faces. Hiro started, face blanching when he truly realized what he was hearing- who he was hearing. He turned, uncaring of the dark mass of microbots that was slowly rising above them all, eyes only for the hunched figure making its way toward them. His breath caught in his throat, choking him where the smoke failed to.

"Ta..."

By the whim of the professor, the microbots slammed into a metal pillar, effectively bending it. There was a groan, the metal shuddering before it gave out. Hiro, eyes wide, looked up to find the beams above him shaking along with the pillar, the weight of the building slowly becoming too much for their support. Parts of metal fell down- rods as big as his forearm, red hot and jagged; Hiro jumped back, increasing the space between him and the man before him (but that didn't matter anymore).

"Tada… shi" He wheezed. He's almost impaled by a cherry-red rod, but too busy searching for the familiar cardigan through the haze of the flames and the waves of heat to care.

The sound of clicking forced his attention back onto Callaghan, the man summoning a number of his microbots and creating a dome-like shield as he hurriedly made his way out of the hall. Another sound came from the floor, Hiro's eyes catching the small shape near the professor, wires sparking and the rubber layer melting because of the heat- _the bomb._

Hiro looked between the bomb and his brother, who was coming ever closer, unsure which course of action he should take. Another groan from above told him he was out of time, more than just small parts of the roof about to come raining down. In an instant, he made his decision; he lunged toward his brother.

"Tadashi!"

And then the bomb went off.

* * *

><p><strong>AN**: Sorry for the long wait. As you can see, it's a pretty long chapter; it took quite some time to get everything we wanted in there. Anyway, hope you enjoyed it! And remember that reviews are always appreciated!


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